JPH06314949A - Surface acoustic wave device - Google Patents
Surface acoustic wave deviceInfo
- Publication number
- JPH06314949A JPH06314949A JP10311593A JP10311593A JPH06314949A JP H06314949 A JPH06314949 A JP H06314949A JP 10311593 A JP10311593 A JP 10311593A JP 10311593 A JP10311593 A JP 10311593A JP H06314949 A JPH06314949 A JP H06314949A
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- Prior art keywords
- electrode
- input
- acoustic wave
- interval
- surface acoustic
- Prior art date
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- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、弾性表面波装置、例え
ば縦結合２重モード弾性表面波共振子型フィルタに関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device, for example, a longitudinally coupled double mode surface acoustic wave resonator type filter.
【０００２】[0002]
【従来の技術】弾性表面波共振子は基本波による直接発
振が得られ、且つ高いＱが得られる上、小型軽量化が可
能であるため、ＶＨＦ〜ＵＨＦ帯の周波数領域で広く用
いられ、ＴＶチューナーや各種無線電話、通信機器に応
用されている。また、その共振特性を圧電基板表面に形
成する電極設計によりコントロールできるため、設計自
由度が大きいという特徴がある。その中で、縦結合２重
モード弾性表面波共振子型フィルタ（以下、２ポート共
振子型フィルタという）は、挿入損失が小さく、通過帯
域幅を比較的大きく取れるという利点があり、無線電話
や通信機器のアンテナフィルタや第１中間周波フィルタ
に使用されるようになっている。2. Description of the Related Art A surface acoustic wave resonator is widely used in the frequency range of VHF to UHF band because it can directly oscillate by a fundamental wave, has a high Q, and can be made compact and lightweight. It has been applied to tuners, various wireless phones, and communication devices. Further, since the resonance characteristic can be controlled by the electrode design formed on the surface of the piezoelectric substrate, there is a feature that the degree of freedom in design is large. Among them, the longitudinally coupled dual-mode surface acoustic wave resonator type filter (hereinafter referred to as a two-port resonator type filter) has advantages that it has a small insertion loss and a relatively large pass band width. It is used for an antenna filter and a first intermediate frequency filter of communication equipment.
【０００３】図８に従来の弾性表面波装置の一例である
２ポート共振子型フィルタを示す。FIG. 8 shows a two-port resonator type filter which is an example of a conventional surface acoustic wave device.
【０００４】２ポート共振子型フィルタ１は、圧電基板
２表面に、電極周期Ｌの入力用交叉指状電極３と電極周
期Ｌの出力用交叉指状電極４とが近接配置されている。
また、前記入出力用交叉指状電極３、４の弾性波伝搬方
向の両側にグレーティング反射器５、６を配置されてい
る。In the two-port resonator type filter 1, an input interdigital electrode 3 having an electrode period L and an output interdigital electrode 4 having an electrode period L are arranged close to each other on a surface of a piezoelectric substrate 2.
Further, grating reflectors 5 and 6 are arranged on both sides of the input / output interdigital electrodes 3 and 4 in the elastic wave propagation direction.
【０００５】ここでは、入力用交叉指状電極３と出力用
交叉指状電極４との間隔を単に間隔ｌ1 といい、入力用
交叉指状電極３とグレーティング反射器５との間隔を単
に間隔ｌ2 といい、出力用交叉指状電極４とグレーティ
ング反射器６との間隔を単に間隔ｌ3 という。また、入
力用及び出力用の各交叉指状電極４、５の電極周期をＬ
と表す。Here, the interval between the input interdigital electrode 3 and the output interdigital electrode 4 is simply referred to as the interval l 1, and the interval between the input interdigital electrode 3 and the grating reflector 5 is simply separated. called l 2, simply referred to as spacing l 3 the distance between the output interdigital electrodes 4 and the grating reflectors 6. Further, the electrode period of each of the interdigitated electrodes 4 and 5 for input and output is set to L
Express.
【０００６】このような２ポート共振子型フィルタで
は、一対のグレーティング反射器５、６間で定在波が生
じ、その定在波を各交叉指状電極３、４で励振、受信す
るという原理で動作している。ここで、定在波が最大に
生じ、所望のフィルタ特性を得るように、間隔ｌ1 、ｌ
2 、ｌ3 が所定値に設定される。In such a 2-port resonator type filter, a standing wave is generated between the pair of grating reflectors 5 and 6, and the standing wave is excited and received by each of the interdigital electrodes 3 and 4. Is working on. Here, in order to maximize the standing wave and obtain the desired filter characteristic, the intervals l 1 , l
2 and l 3 are set to predetermined values.
【０００７】例えば、特開昭６１−１９２１１２号公報
や特開昭６１−１９２１１２号公報などには、２ポート
共振子型フィルタの交叉指状電極４、５の電極周期Ｌ、
間隔ｌ1 、ｌ2 、ｌ3 との関係が開示されている。For example, in JP-A-61-192112 and JP-A-61-192112, the electrode period L of the interdigitated electrodes 4, 5 of a two-port resonator type filter,
The relationship with the intervals l 1 , l 2 , l 3 is disclosed.
【０００８】例えば、特開昭６１−１９２１１２号で
は、（２ｎ＋１）Ｌ／４＜ｌ1 ＜（ｎ＋１）Ｌ／２、
（但し、ｎ＝０、１、２・・・）で、且つ、（４ｍ＋
１）Ｌ／８＜ｌ2 、ｌ3 ＜（４ｍ＋７）Ｌ／８ （ｍ＝
０、 １、 ２・・・）とすることにより、複数の共振モー
ドを近接して存在させ、それによって通過帯域幅を広
げ、帯域内が平坦な特性を実現している。また、特開昭
６３−２８３３０９号公報では、さらに間隔ｌ1 、
ｌ2 、ｌ3 範囲に限定を加え、一層Ｑ値を高めている。For example, in Japanese Patent Laid-Open No. 61-192112, (2n + 1) L / 4 <l 1 <(n + 1) L / 2,
(However, n = 0, 1, 2, ...) And (4m +
1) L / 8 <l 2 , l 3 <(4m + 7) L / 8 (m =
., 0, 1, 2, ...), a plurality of resonance modes are present close to each other, thereby widening the pass band width and realizing a flat characteristic in the band. Further, in Japanese Patent Laid-Open No. 63-283309, further, the interval l 1 ,
The Q value is further increased by limiting the l 2 and l 3 ranges.
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、本発明
者らが、上述の電極周期Ｌ、間隔ｌ1 、ｌ2 、ｌ3 との
関係で種々の実験を行った結果、上記の範囲では、通過
帯域近傍に大きなスプリアスが発生し、所望の減衰特性
を得ることが出来ないという問題のあることを知見し
た。However, as a result of various experiments conducted by the present inventors in relation to the electrode period L and the intervals l 1 , l 2 , and l 3 described above, as a result, in the above range, We have found that there is a problem in that a large spurious is generated near the band and the desired attenuation characteristics cannot be obtained.
【００１０】例えば、特開昭６１−１９２１１２号公報
の範囲（ｌ1 ＝０．９４Ｌ、ｌ2 、ｌ3 ＝０．５Ｌ）で
形成したフィルタの周波数特性を図９に示すが、通過帯
域近傍に大きなスプリアス（特性図中矢印で示す）が生
じ、高域側の減衰が小さく、通信機器の第１中間周波フ
ィルタなどに用いるには不適な特性であった。For example, FIG. 9 shows the frequency characteristics of a filter formed in the range of Japanese Patent Laid-Open No. 61-192112 (l 1 = 0.94L, l 2 , l 3 = 0.5L). A large spurious noise (indicated by an arrow in the characteristic diagram) was generated on the high frequency side, and the attenuation on the high frequency side was small, so that the characteristic was not suitable for use in the first intermediate frequency filter of communication equipment.
【００１１】このスプリアスは様々な原因で発生するこ
とが考えられるが、本発明者らの実験によれば、基本的
には、交叉指状電極３、４から発生する表面波の進行波
とグレーティング反射器５、６から反射される反射波と
の干渉に起因するものが最も影響することが解った。It is considered that the spurious noises are generated by various causes, but according to the experiments by the present inventors, basically, the traveling wave of the surface wave generated from the interdigitated electrodes 3 and 4 and the grating. It was found that those caused by the interference with the reflected waves reflected from the reflectors 5 and 6 had the greatest influence.
【００１２】本発明は上述の課題に鑑みて案出したもの
であり、その目的は、通過帯域近傍のスプリアスを除去
して、減衰が充分に大きくとれ、さらに挿入損失が小さ
く、帯域内特性が平坦化された周波数特性が得られる弾
性表面波装置を提供するものである。The present invention has been devised in view of the above problems, and an object thereof is to remove spurious near the pass band so that attenuation is sufficiently large, insertion loss is small, and in-band characteristics are low. It is intended to provide a surface acoustic wave device capable of obtaining a flattened frequency characteristic.
【００１３】[0013]
【課題を解決するための手段】本発明によれば、圧電基
板表面に、電極周期Ｌの入力用交叉指状電極と電極周期
Ｌの出力用交叉指状電極とを近接配置するとともに、前
記入出力用交叉指状電極の弾性波伝搬方向の両側にグレ
ーティング反射器を配置した弾性表面波装置において、
前記入力用交叉指状電極と出力用交叉指状電極との間隔
をｌａ、前記入出力用交叉指状電極とグレーティング反
射器との間隔をｌｂとした時、電極周期Ｌ、間隔ｌａ及
び間隔ｌｂの関係が （ｎ＋０．３）Ｌ／２＜ｌａ＜（ｎ＋０．４５）Ｌ／
２：（但し、ｎ＝１、２、３・・・）であり、且つ ｌｂ＝ｍＬ／２：（但し、ｍ＝１、２、３・・・）の弾
性表面波装置である。According to the present invention, an input interdigitated electrode having an electrode period L and an output interdigitated electrode having an electrode period L are arranged close to each other on the surface of a piezoelectric substrate, and the input electrode In a surface acoustic wave device in which grating reflectors are arranged on both sides of the output interdigital electrode in the acoustic wave propagation direction,
When the distance between the input interdigital electrode and the output interdigital electrode is la and the distance between the input / output interdigital electrode and the grating reflector is lb, the electrode period L, the interval la, and the interval lb. Is (n + 0.3) L / 2 <la <(n + 0.45) L /
2: (however, n = 1, 2, 3 ...) And lb = mL / 2: (however, m = 1, 2, 3 ...) It is a surface acoustic wave apparatus.
【００１４】[0014]
【作用】弾性表面波装置、特に２ポート共振子型フィル
タでは、原理的にはグレーティング反射器間で発生す
る、両端が節になってエネルギーが閉じこめられた定在
波中で、各交叉指状電極のアース側が節に、電圧印加側
が腹になるように配置することにより、共振が生ずる。
したがって、この原理からすれば、間隔ｌａやｌｂは、
電極周期（＝表面波の波長）ＬとしたときにＬ／２の整
数倍で良いはずである。しかし、このままでは進行波と
反射波との相互作用などにより所望の減衰特性が得られ
ない。In a surface acoustic wave device, especially a two-port resonator type filter, in principle, in the standing wave generated between the grating reflectors, the energy is confined by the nodes at both ends, and each cross finger shape Resonance occurs by arranging the electrodes so that the ground side is the node and the voltage application side is the belly.
Therefore, according to this principle, the intervals la and lb are
When the electrode period (= wavelength of surface wave) L is set, it should be an integral multiple of L / 2. However, as it is, desired attenuation characteristics cannot be obtained due to the interaction between the traveling wave and the reflected wave.
【００１５】本発明では間隔ｌｂはそのままにして間隔
ｌａのみをＬ／２の整数倍から一定範囲でずらす。In the present invention, the interval lb is left as it is and only the interval la is shifted within a certain range from an integral multiple of L / 2.
【００１６】これにより、進行波と反射波の干渉により
生ずるスプリアスの生ずる周波数は、主に上記入力用交
叉指状電極と出力用交叉指状電極との間隔ｌａに依存
し、この間隔ｌａを上記の範囲に選択することにより、
小さい挿入損失を維持したまま、スプリアスを通過帯域
近傍から除去するか、消滅させることができる。As a result, the frequency of the spurious generated by the interference between the traveling wave and the reflected wave mainly depends on the distance la between the input interdigital electrode and the output interdigital electrode, and this space la is defined as above. By selecting the range of
Spurious can be removed or eliminated from near the pass band while maintaining a small insertion loss.
【００１７】この時、グレーティング反射器間で定在波
を生じさせる条件はその間隔がＬ／２の整数倍であるた
め、間隔ｌａ、ｌｂ共に、各々Ｌ／２の整数倍ずつずら
した位置でも概略同じ共振特性が得られる。At this time, the condition for producing a standing wave between the grating reflectors is that the interval is an integral multiple of L / 2, and therefore both the intervals la and lb are also shifted by an integer multiple of L / 2. Approximately the same resonance characteristics are obtained.
【００１８】[0018]
【実施例】次に本発明の弾性表面波装置を図面に基づい
て説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a surface acoustic wave device of the present invention will be described with reference to the drawings.
【００１９】図１は本発明の弾性表面波装置、特に２ポ
ート共振子型フィルタ１の平面状態の模式図である。FIG. 1 is a schematic view of a surface acoustic wave device of the present invention, particularly a two-port resonator type filter 1 in a plan view.
【００２０】２ポート共振子型フィルタ１は、圧電基板
２上に入力用交叉指状電極３、出力用交叉指状電極４が
間隔ｌａをおいて近接配置されている。また、それらの
交叉指状電極３、４のを伝搬方向の両側には、一対のグ
レーティング反射器５、６で配置されている。尚、グレ
ーティング反射器５、６と入出力用交叉指状電極３、４
との間隔は、共に同一の間隔ｌｂとなっている。In the two-port resonator type filter 1, an input interdigital electrode 3 and an output interdigital electrode 4 are closely arranged on a piezoelectric substrate 2 with a space la. Further, a pair of grating reflectors 5 and 6 are arranged on both sides of the interdigital electrodes 3 and 4 in the propagation direction. In addition, the grating reflectors 5 and 6 and the interdigital finger electrodes 3 and 4 for input and output.
The intervals between and are the same as each other.
【００２１】また、入出力用交叉指状電極３、４とも
に、電極を構成する一方の櫛歯電極間の間隔は（電極周
期）はＬとなっている。また、グレーティング反射器
５、６のグレーティング周期は略Ｌ／２である。Further, in both the I / O interdigitated electrodes 3 and 4, the interval (electrode period) between the one comb-teeth electrodes forming the electrodes is L. The grating period of the grating reflectors 5 and 6 is approximately L / 2.
【００２２】入力用交叉指状電極３の一方の電極指３ａ
は入力側に接続され、他方の電極指３ｂは接地されてい
る。また、出力用交叉指状電極４の一方の電極指４ａは
接地され、他方の電極指４ｂは出力側に接続される。One electrode finger 3a of the input interdigital electrode 3
Is connected to the input side, and the other electrode finger 3b is grounded. Further, one electrode finger 4a of the output cross-finger electrode 4 is grounded, and the other electrode finger 4b is connected to the output side.
【００２３】（実施例１）圧電基板２として表面を完全
に研磨した４ほう酸リチウム（４５゜Ｘカット、Ｚ伝
播）板を用い、その表面に図１のような、入力用交叉指
状電極３、出力用交叉指状電極４、グレーティング反射
器５、６を形成した。このフィルタの中心周波数２４８
ＭＨｚの２ポート共振子型フィルタを製作した。Example 1 A lithium tetraborate (45 ° X-cut, Z-propagation) plate having a completely polished surface was used as a piezoelectric substrate 2, and an input interdigital electrode 3 as shown in FIG. 1 was used on the surface. The output interdigital electrode 4 and the grating reflectors 5 and 6 were formed. Center frequency 248 of this filter
A 2-port resonator type filter of MHz was manufactured.
【００２４】入力用交叉指状電極３、出力用交叉指状電
極４、グレーティング反射器５、６は、具体的には、圧
電基板２に電極材料であるアルミニウムを真空蒸着で膜
厚１．２μｍで形成した後、フォトプロセスで所定パタ
ーンを形成し、リフトオフ法で不要部を剥離した。The input interdigital electrode 3, the output interdigital electrode 4, and the grating reflectors 5 and 6 are, specifically, made of aluminum, which is an electrode material, on the piezoelectric substrate 2 by vacuum vapor deposition to have a film thickness of 1.2 μm. Then, a predetermined pattern was formed by a photo process, and unnecessary portions were peeled off by a lift-off method.
【００２５】この場合、電極指周期Ｌ＝１３．８μｍで
あり、電極指の交叉幅は１０Ｌ（＝１３８μｍ）とし
た。交叉指の対数は、励振側４０対、受信側４０対の計
８０対とし、グレーティング反射器５、６のグレーティ
ング数は、各々１００本の計２００本とした。In this case, the electrode finger period L = 13.8 μm, and the electrode finger cross width was 10 L (= 138 μm). The number of pairs of crossing fingers was set to 80 pairs, that is, 40 pairs on the excitation side and 40 pairs on the reception side, and the number of gratings of the grating reflectors 5 and 6 was set to 200 pieces, that is, 100 pieces each.
【００２６】ここで、グレーティング反射器５、６と交
叉指状電極３、４の間隔ｌｂを、ｌｂ＝０．５Ｌと一定
にし、入力用交叉指状電極３と出力用交叉指状電極４と
の間隔ｌａを本発明の範囲内で種々変化させて実験し、
フィルタの周波数特性を測定した。この結果を図３乃至
図５に示す。これらの特性図において、横軸は周波数
（１ＭＨｚ／div ）であり、縦軸は減衰量（１０ｄＢ／
div ）である。Here, the interval lb between the grating reflectors 5 and 6 and the interdigitated electrodes 3 and 4 is kept constant at lb = 0.5 L, and the interdigitated electrode for input 3 and the interdigitated electrode for output 4 are connected. Experiments were performed by changing the interval la of variously within the scope of the present invention,
The frequency characteristic of the filter was measured. The results are shown in FIGS. In these characteristic diagrams, the horizontal axis represents frequency (1 MHz / div) and the vertical axis represents attenuation (10 dB / div).
div).
【００２７】本発明における好適な間隔ｌａの範囲は、
ｎ＝１の時、０．６５＜ｌａ＜０．７２５であるが、ｌ
ａが０．６６２５であって本発明の下限に近い図３の例
においては、低周波側に若干スプリアスの影響による減
衰域での裾引きが見られるが、実用可能な範囲である。The preferred range of the distance la in the present invention is
When n = 1, 0.65 <la <0.725, but l
In the example of FIG. 3 in which a is 0.6625, which is close to the lower limit of the present invention, there is some tailing in the attenuation range due to the influence of spurious on the low frequency side, but this is within the practical range.
【００２８】一方、間隔ｌａが上限に近い０．７１２５
である図５の例においては、高周波側に発生するスプリ
アスの影響により減衰域での裾引きが見られるが、同じ
く実用可能な範囲である。On the other hand, the interval la is 0.7125, which is close to the upper limit.
In the example of FIG. 5, which has a tail in the attenuation region due to the influence of spurious generated on the high frequency side, it is also within a practical range.
【００２９】図４の例においては間隔ｌａが０．６８７
５で、好適範囲の中央値であり、低周波側高周波側共ス
プリアスの影響がなく、大きい減衰量が取れており、最
も良好な特性を示している。In the example of FIG. 4, the interval la is 0.687.
5, which is the median value of the preferable range, there is no influence of the spurious on the low frequency side and the high frequency side, a large amount of attenuation is obtained, and the best characteristics are exhibited.
【００３０】これらの特性図から、間隔ｌａが本発明の
下限値未満では低周波側にスプリアスが生じ、上限値を
越えると高周波側にスプリアスが生じる傾向のあること
が解る。From these characteristic diagrams, it is understood that spurious tends to occur on the low frequency side when the interval la is less than the lower limit of the present invention, and spurious tends to occur on the high frequency side when the interval la exceeds the upper limit.
【００３１】（実施例２）間隔ｌb ＝Ｌ（即ち、ｍ＝
２）として、間隔ｌａを本発明の範囲内で変化させ、そ
の他の条件は実施例１と同一条件としてフィルタ特性を
測定した結果、いずれも実用可能な特性が得られた。(Embodiment 2) Interval lb = L (that is, m =
As 2), the interval la was changed within the range of the present invention, and other conditions were the same as those in Example 1, and the filter characteristics were measured. As a result, practically usable characteristics were obtained.
【００３２】（実施例３）間隔ｌｂ＝Ｌ（即ち、ｍ＝
２）として、１．１５＜ｌａ＜１．２２５（即ち、ｎ＝
２）の範囲内で変化させ、その他の条件は実施例１と同
一条件としてフィルタ特性を測定した結果、いずれも実
用可能な特性が得られた。(Embodiment 3) Interval lb = L (that is, m =
2) as 1.15 <la <1.225 (that is, n =
As a result of changing the filter characteristics within the range of 2) and measuring the filter characteristics under the same conditions as in Example 1 except for the above, practically applicable characteristics were obtained.
【００３３】（実施例４）実施例１の図４の条件で製作
した２ポート共振子型フィルタを２段縦列接続したバン
ドパスフィルタを試作した。そのフィルタ特性を図６に
示す。更にこのフィルタの入出力部分及び２段縦列接続
部の段間にＬ、Ｃ、Ｒ等を付加してインピーダンス整合
を図ることによって、図７のような特性が得られ、帯域
内特性が平坦化され、減衰も十分大きい優れた特性が得
られた。(Embodiment 4) A band-pass filter in which two-port resonator filters manufactured under the conditions of FIG. The filter characteristic is shown in FIG. Further, by adding L, C, R, etc. between the input / output part of this filter and the stage of the two-stage cascade connection part to achieve impedance matching, the characteristic as shown in FIG. 7 is obtained and the in-band characteristic is flattened. Therefore, excellent characteristics were obtained with large attenuation.
【００３４】（比較例）間隔ｌａ＝０．５６２５、間隔
ｌｂ＝０．５Ｌとして間隔ｌａのみ本発明の下限値未満
とし、その他の条件は実施例１と同一条件としてフィル
タ特性を測定した結果、図２に示すように低周波側にス
プリアス（特性図中矢印で表示）が生じ、実用には不適
な特性であった。(Comparative Example) As a result of measuring the filter characteristics under the same conditions as in Example 1 except that the interval la is set to 0.5625 and the interval lb is set to 0.5L, only the interval la is less than the lower limit of the present invention. As shown in FIG. 2, spurious (indicated by an arrow in the characteristic diagram) was generated on the low frequency side, and the characteristic was not suitable for practical use.
【００３５】上記の実施例のように、間隔ｌａが本発明
の下限値未満では低周波側にスプリアスが生じ、上限値
を越えると高周波側にスプリアスが生じる傾向のあるこ
とが言える。It can be said that when the distance la is less than the lower limit of the present invention as in the above embodiment, spurious tends to occur on the low frequency side and when it exceeds the upper limit the spurious tends to occur on the high frequency side.
【００３６】また、その他の多くの実験により、低周波
側、高周波側いずれに生じるスプリアスにおいても、間
隔ｌａを大きくするとスプリアスが低周波側に移動する
傾向があることが解った。Also, from many other experiments, it has been found that, with respect to spurious generated on both the low frequency side and the high frequency side, the spurious tends to move to the low frequency side when the interval la is increased.
【００３７】本発明の範囲内では、低周波側、高周波側
の両方のスプリアス共に通過帯域の周波数からはずれた
位置にあるが、間隔ｌａを本発明の下限値より小さくす
ると低周波側のスプリアスが高周波側に移動して通過帯
域に接近し、間隔ｌａを本発明の上限値より大きくする
と高周波側のスプリアスが低周波側に移動して通過帯域
に接近して何れも減衰の低下をもたらす。Within the scope of the present invention, both the spurious on the low frequency side and the spurious on the high frequency side are located out of the frequency of the pass band. When it moves to the high frequency side and approaches the pass band, and the interval la is made larger than the upper limit value of the present invention, the spurious on the high frequency side moves to the low frequency side and approaches the pass band, and in both cases, attenuation is reduced.
【００３８】これらのスプリアスが具体的にどのような
メカニズムで生じているのかは未だ十分解明されてはい
ないが、本発明者らは、繰り返し実験を行っても上述の
傾向は再現されることを確認した。Although the specific mechanism by which these spurs are generated has not been fully clarified yet, the present inventors have found that the above tendency can be reproduced even after repeated experiments. confirmed.
【００３９】なお、本発明では４ほう酸リチウム基板を
用いた場合に好適に適用されることが示されたが、上記
実施例に限定されず、他の基板を用いた場合でも適用で
きると考える。Although the present invention has been shown to be preferably applied to the case of using a lithium tetraborate substrate, it is not limited to the above-mentioned embodiment, and it is considered that the present invention can be applied to the case of using another substrate.
【００４０】[0040]
【発明の効果】以上の通り、本発明の弾性表面波装置、
特に２ポート共振子型フィルタによれば、入力用交叉指
状電極と出力用交叉指状電極との間隔ｌａを、入出力用
交叉指状電極の電極周期Ｌに対して所定の範囲に選択す
ることにより、通過帯域付近のスプリアスを除去して減
衰を充分大きく取ることができる。As described above, the surface acoustic wave device of the present invention,
Particularly, according to the 2-port resonator type filter, the interval la between the input interdigital electrode and the output interdigital electrode is selected within a predetermined range with respect to the electrode period L of the input / output interdigital electrode. As a result, spurious near the pass band can be removed and the attenuation can be made sufficiently large.
【００４１】その結果、挿入損失が小さく、帯域内特性
が平坦化された周波数特性が得られ、通信機器の第１中
間周波フィルタなどの用途に最適な特性が実現される。As a result, the insertion loss is small and the frequency characteristic with the flattened in-band characteristic is obtained, and the characteristic optimal for the application such as the first intermediate frequency filter of the communication device is realized.
【図１】本発明の弾性表面波装置、特に２ポート共振子
型フィルタの平面図である。FIG. 1 is a plan view of a surface acoustic wave device of the present invention, particularly a two-port resonator type filter.
【図２】本発明の比較例のフィルタ特性を示す特性図で
ある。FIG. 2 is a characteristic diagram showing a filter characteristic of a comparative example of the present invention.
【図３】本発明のフィルタ特性を示す特性図である。FIG. 3 is a characteristic diagram showing a filter characteristic of the present invention.
【図４】本発明のフィルタ特性を示す特性図である。FIG. 4 is a characteristic diagram showing a filter characteristic of the present invention.
【図５】本発明のフィルタ特性を示す特性図である。FIG. 5 is a characteristic diagram showing a filter characteristic of the present invention.
【図６】本発明の弾性表面波装置、特に２ポート共振子
型フィルタを２段に縦列接続した弾性表面波装置のフィ
ルタ特性を特性図である。FIG. 6 is a characteristic diagram showing the filter characteristics of a surface acoustic wave device of the present invention, particularly a surface acoustic wave device in which two-port resonator filters are cascaded in two stages.
【図７】本発明の弾性表面波装置、特に２ポート共振子
型フィルタを２段に縦列接続した弾性表面波装置のフィ
ルタ特性を特性図である。FIG. 7 is a characteristic diagram showing the filter characteristics of a surface acoustic wave device of the present invention, particularly a surface acoustic wave device in which two-port resonator filters are cascaded in two stages.
【図８】従来の２ポート共振子型フィルタの平面図であ
る。FIG. 8 is a plan view of a conventional 2-port resonator type filter.
【図９】従来のフィルタ特性を示す特性図である。FIG. 9 is a characteristic diagram showing conventional filter characteristics.
１・・・２ポート共振子型フィルタ ２・・・圧電基板 ３・・・入力用交叉指状電極 ４・・・出力用交叉指状電極 ５、６・・グレーティング反射器 1 ... 2-port resonator type filter 2 ... Piezoelectric substrate 3 ... Input interdigital electrode 4 ... Output interdigital electrode 5, 6, ... Grating reflector
Claims (1)
叉指状電極と出力用交叉指状電極とを近接配置するとと
もに、前記入出力用交叉指状電極の弾性波伝搬方向の両
側にグレーティング反射器を配置した弾性表面波装置に
おいて、前記入力用交叉指状電極と出力用交叉指状電極
との間隔をｌａ、前記入出力用交叉指状電極とグレーテ
ィング反射器との間隔をｌｂとした時、電極周期Ｌ、間
隔ｌａ及び間隔ｌｂの関係が （ｎ＋０．３）Ｌ／２＜ｌａ＜（ｎ＋０．４５）Ｌ／
２：（但し、ｎ＝１、２、３・・・）であり、且つ ｌｂ＝ｍＬ／２、（但し、ｍ＝１、２、３・・・） であることを特徴とする弾性表面波装置。1. An input interdigitated electrode and an output interdigitated electrode having an electrode period L are arranged in proximity to each other on a surface of a piezoelectric substrate, and both sides of the input / output interdigitated electrode in the elastic wave propagation direction. In a surface acoustic wave device in which a grating reflector is arranged, the distance between the input interdigital electrode and the output interdigital electrode is la, and the distance between the input / output interdigital electrode and the grating reflector is lb. Then, the relationship between the electrode period L, the interval la, and the interval lb is (n + 0.3) L / 2 <la <(n + 0.45) L /
2: (however, n = 1, 2, 3 ...) And lb = mL / 2, (however, m = 1, 2, 3, ...) apparatus.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10311593A JPH06314949A (en) | 1993-04-28 | 1993-04-28 | Surface acoustic wave device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10311593A JPH06314949A (en) | 1993-04-28 | 1993-04-28 | Surface acoustic wave device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06314949A true JPH06314949A (en) | 1994-11-08 |
Family
ID=14345603
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10311593A Pending JPH06314949A (en) | 1993-04-28 | 1993-04-28 | Surface acoustic wave device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06314949A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6215845B1 (en) | 1999-10-18 | 2001-04-10 | General Mills, Inc. | Detection of variable positionable missing components utilizing x-rays |
-
1993
- 1993-04-28 JP JP10311593A patent/JPH06314949A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6215845B1 (en) | 1999-10-18 | 2001-04-10 | General Mills, Inc. | Detection of variable positionable missing components utilizing x-rays |
| WO2001028864A1 (en) * | 1999-10-18 | 2001-04-26 | General Mills, Inc. | Device for detecting missing components utilizing x-rays |
| US6335960B2 (en) | 1999-10-18 | 2002-01-01 | General Mills, Inc. | Detection of variable manufacturing tolerance packages utilizing x-rays |
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